The 747 was being operated on a scheduled passenger flight from Singapore to Frankfurt with four pilots, 14 cabin crew and 378 passengers. At the time of flight planning in Singapore, the terminal aerodrome forecast for Frankfurt indicated CAVOK conditions at the estimated time of arrival (ETA), and there was no requirement to plan for an alternate aerodrome. The fuel uplift at Singapore for the flight to Frankfurt was in accordance with the operators’ Civil Aviation Safety Authority (CASA) of Australia-approved fuel policy. The 747 departed Singapore on 27 July at 1521. The ETA for Frankfurt was 0319 on 28 July. The 0220 Frankfurt routine aviation weather report obtained by the crew included information that CAVOK conditions existed, with no significant changes expected. The crew of the 747 commenced descent into Frankfurt at about 0300, and the Frankfurt automatic terminal information service provided the crew with information that CAVOK conditions existed. As the 747 approached position GED, which was 35 NM from Frankfurt, the air traffic controller instructed the crew to enter a holding pattern at GED. As the 747 was in the holding pattern, radio transmissions from the crews of other aircraft alerted the crew of the 747 that the weather conditions at Frankfurt had suddenly deteriorated, and that there were thunderstorms and heavy rain showers at the aerodrome. The crew elected to divert the 747 to Munich, where it landed without further incident. A number of other international flights were similarly affected. Because of the unexpected and unscheduled diversion from Frankfurt, the reserve fuel remaining on board the 747 when it arrived at Munich was less than that required by the operators CASA approved fuel policy for the planned flight. Note: CAVOK conditions are: Visibility 10 km or more; No cloud below 5,000 ft or below the highest minimum sector altitude, whichever is the greater, and no cumulonimbus; No precipitation, thunderstorm, shallow fog, low drifting snow or dust devils.3. How did the crew get the information that CAVOK condition existed in Frankfurt when the 747 commenced descent?